Injection molding flow control apparatus and method

ABSTRACT

An apparatus for controlling the rate of flow of mold material to a mold cavity, the apparatus comprising: an injection molding machine and a manifold; an actuator interconnected to a valve pin having a tip end; a valve system in fluid communication with the actuator to drive the actuator at one or more rates of travel, the valve system having a start position, one or more intermediate drive rate positions and a high drive rate position, the start position holding the valve pin in a gate closed position; a controller that instructs the valve system to move from the start position to the one or more intermediate drive rate positions and to remain in the one or more intermediate drive rate positions for one or more corresponding predetermined amounts of time.

RELATED APPLICATIONS

This application is a continuation and claims the benefit of priority toU.S. application Ser. No. 15/453,019 filed Mar. 8, 2016, which is acontinuation and claims the benefit of priority to U.S. application Ser.No. 14/567,308 filed Dec. 11, 2014 which is a divisional and claims thebenefit of priority to U.S. application Ser. No. 13/484,408 filed May31, 2012, which is a continuation of and claims the benefit of priorityto PCT/US11/62096 filed Nov. 23, 2011, which claims the benefit ofpriority to U.S. Provisional Application Ser. No. 61/475,340 filed Apr.14, 2011 and to U.S. Provisional Application Ser. No. 61/416,583 filedNov. 23, 2010, the disclosures of all of the foregoing of which areincorporated by reference herein in their entirety as if fully set forthherein.

The disclosures of all of the following are incorporated by reference intheir entirety as if fully set forth herein: U.S. Pat. No. 5,894,025,U.S. Pat. No. 6,062,840, U.S. Pat. No. 6,294,122, U.S. Pat. No.6,309,208, U.S. Pat. No. 6,287,107, U.S. Pat. No. 6,343,921, U.S. Pat.No. 6,343,922, U.S. Pat. No. 6,254,377, U.S. Pat. No. 6,261,075, U.S.Pat. No. 6,361,300, U.S. Pat. Nos. 6,419,870, U.S. Pat. No. 6,464,909,U.S. Pat. No. 6,599,116, U.S. Pat. No. 7,234,929, U.S. Pat. No.7,419,625, U.S. Pat. No. 7,569,169, U.S. patent application Ser. No.10/214,118, filed Aug. 8, 2002, U.S. Pat. No. 7,029,268, U.S. Pat. No.7,270,537, U.S. Pat. No. 7,597,828, U.S. patent application Ser. No.09/699,856 filed Oct. 30, 2000, U.S. patent application Ser. No.10/269,927 filed Oct. 11, 2002, U.S. application Ser. No. 09/503,832filed Feb. 15, 2000, U.S. application Ser. No. 09/656,846 filed Sep. 7,2000, U.S. application Ser. No. 10/006,504 filed Dec. 3, 2001, and U.S.application Ser. No. 10/101,278 filed Mar. 19, 2002.

BACKGROUND OF THE INVENTION

Injection molding systems have been developed having flow controlmechanisms that control the movement of a valve pin over the course ofan injection cycle to cause the pin to move either upstream ordownstream over the course of an injection cycle in order to raise orlower the rate of flow of fluid material into the cavity to correspondto a predetermined profile of fluid flow rates over the length of theinjection cycle. A sensor is used to sense a condition of the fluidmaterial or of the apparatus, the sensor sending a signal indicative ofthe sensed condition to a program contained in a controller that usesthe signal as a variable to control movement of the valve pin inaccordance with the predetermined profile.

SUMMARY OF THE INVENTION

In accordance with the invention there is provided a method ofperforming an injection molding cycle in an injection molding apparatuscomprising:

-   an injection molding machine and a manifold that receives an    injected mold material from the injection molding machine, the    manifold having a delivery channel that delivers the mold material    under an injection pressure to a first gate of a mold cavity,-   an actuator interconnected to a valve pin driving the valve pin from    a first position where the tip end of the valve pin obstructs the    gate to prevent the injection fluid material from flowing into the    cavity, upstream to a second position upstream of the gate where the    mold material flows at a maximum rate through the gate and    continuously upstream from the start position through one or more    intermediate positions between the first position and the second    position wherein the tip end of the valve pin restricts flow of the    injection mold material to one or more rates less than the maximum    rate,-   a valve system for controllably driving the valve pin, the valve    system being controllably movable from a start position to one or    more intermediate drive rate positions and a high drive rate    position, the high drive rate position driving the pin upstream at a    high rate of travel, the intermediate drive rate positions driving    the pin upstream at one or more intermediate rates of travel that    are less than the high rate of travel,    -   the method comprising:    -   selecting one or more lengths of time for the valve system to        operate or reside in corresponding ones of the one or more        intermediate drive rate positions,    -   beginning an injection cycle with the tip end of the valve pin        in the first position and the valve system in the start        position,    -   adjusting the valve system to operate at the one or more of the        intermediate drive rate positions for the one or more selected        lengths of time to drive the valve pin continuously upstream,    -   adjusting the valve system to operate at the high drive rate        position to drive the tip end of the valve pin continuously        upstream at the high rate of travel upon expiration of the one        or more selected lengths of time.

In an alternative embodiment, the method and apparatus can carry out asingle adjustment of the valve system or velocity to cause the valve pinto travel at a less than maximum velocity during the entirety of theinjection cycle all the way from the gate closed position to the maximumend of stroke position.

The valve system is typically adjusted to operate at the one or moreintermediate drive rate positions after the mold material has beeninjected into the cavity through another gate and has travelled throughthe cavity past the first gate. The valve system can be adjusted tooperate at a single intermediate drive rate position for a singleselected length of time.

The valve system is typically interconnected to an electrical signalgenerating device operable to generate electrical signals ofcontrollably variable output, the valve system being adjustable in driverate position to increase the flow of drive fluid to a degree that isproportional to the degree of output of the electrical signals, thesteps of adjusting the valve system comprising operating the electricalsignal generating device to generate electrical signals that adjust thedrive rate positions of the valve system according electrical signals ofselected degree of output.

Each of the drive rate positions of the valve system preferably have adegree of openness, the drive fluid of the valve system driving theactuator and the valve pin at a rate that is proportional to the degreeof openness of the positions of the valve system, the one or moreintermediate drive rate positions having a degree of openness that isless than the degree of openness of the high drive rate flow position.

The length of travel between the first position and the one or moreintermediate positions along the drive path is typically between about 1mm and about 5 mm.

In another embodiment of the invention there is provided an apparatusfor controlling the rate of flow of mold material to a mold cavity, theapparatus comprising:

-   an injection molding machine and a manifold that receives the    injected mold material from the machine, the manifold having a    delivery channel that delivers the mold material at one or more flow    rates through a gate to the mold cavity,-   an actuator interconnected to a valve pin having a tip end, the    actuator being drivable to move the valve pin along a path of travel    starting from a downstream gate closed position continuously    upstream to and through a series of successively upstream    intermediate upstream gate open positions and further continuously    upstream to a high upstream gate open position,-   a valve system in fluid communication with the actuator to drive the    actuator with drive fluid at one or more rates of travel, the valve    system having a start position, one or more intermediate drive rate    positions and a high drive rate position, the start position holding    the valve pin in the gate closed position, the high drive rate    position driving the actuator upstream at a maximum velocity under    which the valve system is capable of driving the actuator, the one    or more intermediate drive rate positions driving the actuator    upstream at one or more corresponding velocities that are less than    the maximum velocity,-   a controller interconnected to the valve system, the controller    being adapted to control movement of the valve system between the    start position, the one or more intermediate drive rate positions    and the high drive rate position,-   the controller including an electrical signal generator that drives    the valve system to move from the start position to the one or more    intermediate drive rate positions and to remain in the one or more    intermediate drive rate positions for one or more corresponding    predetermined amounts of time and further drives the valve system to    move from the one or more intermediate drive rate positions to the    high drive rate position on expiration of the one or more    predetermined amounts of time.

The positions of the valve system preferably each have a correspondingdegree of openness, the controller being adapted to generate anelectrical signal of selectable degree of output, the degree of opennessof the positions of the valve system being proportional to the degree ofoutput of the electrical signal generated by the controller.

The output of the electrical signal can one or more of electricalenergy, electrical power, voltage, current or amperage.

The degree of openness of the positions of the valve system each have acorresponding rate of flow of the drive fluid that is proportional tothe corresponding degree of openness of the positions of the valvesystem.

The tip end of the valve pin typically obstructs the gate to prevent themold material from flowing into the cavity in the first position, themold material flows at a maximum rate through the gate in the secondposition and the tip end of the valve pin restricts the flow of the moldmaterial to less than the maximum rate in the one or more intermediateupstream positions between the first position and the second position,and wherein

-   the valve pin is in one or more of the intermediate upstream    positions when the valve system is in the one or more intermediate    drive rate positions.

The rate of travel of the actuator that corresponds to a highest of theone or more intermediate drive rate positions of the valve system isless than about 75% of the rate of travel of the actuator thatcorresponds to the high drive rate position of the valve system.

Each of the positions of the valve system preferably have acorresponding degree of openness, the actuator being driven at avelocity that is proportional to the degree of openness of the positionsof the valve system, the electrical signals generated by the controllereach having a degree of output that adjusts the valve system to a degreeof openness that is proportional to the degree of output of theelectrical signals.

The controller is programmable to automatically generate one or morefirst electrical signals having one or more corresponding first selecteddegrees of output that move the valve system to the one or moreintermediate drive rate positions to drive the actuator continuouslyupstream at one or more corresponding first velocities that are lessthan the maximum velocity, the controller generating a second electricalsignal on expiration of the one or more predetermined amounts of time,the second electrical signal having a second selected degree of outputthat moves the valve system to the high drive rate position to drive theactuator at the maximum velocity.

The controller typically includes electrical or electronic instructionsinterconnected to an electrical signal generator that automaticallyinstructs the electrical signal generator to generate the electricalsignals that drive the valve system to move from the start position tothe one or more intermediate drive positions and to remain in the one ormore intermediate drive positions for the one or more predeterminedamounts of time and further instructs the electrical signal generator togenerate an electrical signal that drives the valve system to move fromthe one or more intermediate drive positions to the high drive positionon expiration of the one or more predetermined amounts of time.

Each of the positions of the valve system have a corresponding degree ofopenness, the actuator being driven at a velocity that is proportionalto the degree of openness of the positions of the valve system, theelectrical signals generated by the controller each having a degree ofoutput that adjusts the valve system to a degree of openness that isproportional to the degree of output of the electrical signals.

The output of the electrical signal can be one or more of electricalenergy, electrical power, voltage, current or amperage.

Further in accordance with the invention there is provided a method ofperforming an injection molding cycle in an injection molding apparatuscomprising:

-   an injection molding machine and a manifold that receives an    injected mold material from the injection molding machine, the    manifold having a delivery channel that delivers the mold material    under an injection pressure to a first gate of a mold cavity,-   an actuator interconnected to a valve pin driving the valve pin from    a first position where the tip end of the valve pin obstructs the    gate to prevent the injection fluid material from flowing into the    cavity, upstream to a second position upstream of the gate where the    mold material flows at a maximum rate through the gate and    continuously upstream from the start position through one or more    intermediate positions between the first position and the second    position wherein the tip end of the valve pin restricts flow of the    mold material to one or more corresponding rates of flow that are    less than the maximum rate,-   a valve system for controllably driving the valve pin, the valve    system being controllably movable from a start position to one or    more intermediate drive rate positions and a high drive rate    position, the high drive rate position driving the pin upstream at a    high rate of travel, the intermediate drive rate positions driving    the pin upstream at one or more intermediate rates of travel that    are less than the high rate of travel,-   the method comprising:-   preselecting one or more lengths of time for the valve system to    reside in the one or more intermediate drive rate positions such    that the tip end of the pin is disposed in a position that restricts    the flow of mold material through the gate to less than the maximum    rate during the entirety of said preselected lengths of time,-   beginning an injection cycle with the tip end of the valve pin in    the first position and the valve system in the start position,-   adjusting the valve system to operate at one or more of the    intermediate drive rate positions for the one or more selected    lengths of time to drive the valve pin continuously upstream,-   adjusting the valve system to operate at the high drive rate    position to drive the tip end of the valve pin continuously upstream    at the high rate of travel upon expiration of the one or more    selected lengths of time.

Such a method typically comprises carrying out the steps of beginningand adjusting automatically via an electrical controller havingprogrammable instructions.

In another aspect of the invention there is provided a method ofperforming an injection molding cycle in an injection molding apparatuscomprising:

-   an injection molding machine and a manifold that receives an    injected mold material from the injection molding machine, the    manifold having a delivery channel that delivers the mold material    under an injection pressure to a first gate of a mold cavity,-   an actuator interconnected to a valve pin driving the valve pin from    a first position where the tip end of the valve pin obstructs the    gate to prevent the injection fluid material from flowing into the    cavity, upstream to a second position upstream of the gate where the    mold material flows at a maximum rate through the gate and    continuously upstream from the start position through one or more    intermediate positions between the first position and the second    position wherein the tip end of the valve pin restricts flow of the    injection fluid to one or more rates less than the maximum rate,-   a drive system for controllably driving the actuator and the valve    pin upstream at one or more selected intermediate velocities and at    one or more high velocities that are higher than the intermediate    velocities,-   the method comprising:-   selecting one or more lengths of time for the drive system to drive    the actuator at the one or more intermediate velocities,-   beginning an injection cycle with the tip end of the valve pin in    the first position,-   adjusting the drive system to drive the actuator at the one or more    intermediate velocities for the one or more selected lengths of time    to drive the valve pin continuously upstream, adjusting the drive    system to drive the actuator at the one or more high velocities to    drive the tip end of the valve pin continuously upstream at the one    or more high velocities upon expiration of the one or more selected    lengths of time.

The drive system can be adjusted to drive the actuator at the one ormore intermediate velocities after the mold material has been injectedinto the cavity through another gate and has travelled through thecavity past the first gate.

The drive system can be adjusted to drive the actuator at a singleintermediate velocity for a single selected length of time.

The drive system can be interconnected to an electrical signalgenerating device operable to generate electrical signals ofcontrollably variable degree of output, the drive system beingadjustable in drive rate to adjust velocity to a degree that isproportional to the degree of output of the electrical signals, thesteps of adjusting the drive system comprising operating the electricalsignal generating device to generate electrical signals thatproportionally adjust the drive rate of the drive system according toelectrical signals having one or more selected degrees of output.

The length of travel between the first position and the one or moreintermediate positions along the drive path is between about 1 mm andabout 5 mm.

In another aspect of the invention there is provided an apparatus forcontrolling the rate of flow of mold material to a mold cavity, theapparatus comprising:

-   an injection molding machine and a manifold that receives the    injected mold material from the machine, the manifold having a    delivery channel that delivers the mold material at one or more flow    rates through a gate to the mold cavity,-   an actuator interconnected to a valve pin having a tip end, the    actuator being drivable to move the valve pin along a path of travel    starting from a downstream gate closed position continuously    upstream to and through a series of successively upstream    intermediate upstream gate open positions and further continuously    upstream to a high upstream gate open position,-   a drive system connected to the actuator, the drive system being    adapted to drive the actuator continuously upstream beginning from    the gate closed position at one or more preselected intermediate    velocities for one or more corresponding selected lengths of time    and further subsequently driving the actuator continuously upstream    at one or more high velocities that are higher than the intermediate    velocities.

Such an apparatus typically further comprises

-   a controller interconnected to the drive system, the controller    being adapted to control operation of the drive system between the    start position, the one or more intermediate drive rate positions    and the high drive rate position,-   the controller including an electrical signal generator that outputs    electrical signals of controllably variable degree of output, the    drive system being adjustable in drive rate to adjust velocity of    the actuator and the valve pin to a degree that is proportional to    the degree of output of the electrical signals,-   the controller including instructions that operate the electrical    signal generating device to generate electrical signals of one or    more preselected degrees of output that drive the actuator upstream    at corresponding ones of the intermediate upstream velocities for    the one or more corresponding selected lengths of time and that    further drive the actuator at the one or more high velocities on    expiration of the selected lengths of time.

The output of the electrical signal can be one or more of electricalenergy, electrical power, voltage, current or amperage.

The tip end of the valve pin preferably obstructs the gate to preventthe mold material from flowing into the cavity when the actuator is inthe downstream gate closed position, the mold material flows at amaximum rate through the gate when the actuator is in the high upstreamgate open position and the tip end of the valve pin restricts the flowof the mold material to less than the maximum rate when the actuator isin the one or more intermediate upstream gate open positions, andwherein the valve pin is in one or more of the intermediate upstreampositions restricting flow of the mold material to less than the maximumrate when the drive system is driving the actuator at the one or moreintermediate velocities.

The rate of travel of the actuator when the actuator is driven at thehighest of the one or more intermediate velocities is less than about75% of the rate of travel of the actuator when the actuator is driven atthe lowest of the one or more high velocities.

The length of travel between the downstream gate closed position and thefurthest upstream of the one or more intermediate upstream gate openpositions is typically between about 1 mm and about 5 mm.

Further in accordance with the invention there is provided asequentially gated molding system comprising a mold having first andsecond gates leading to a common cavity and a manifold having first andsecond fluid flow channels respectively delivering a fluid mold materialthrough the first and second gates into the cavity, the systemcomprising:

-   a first valve controlling delivery of the fluid material through the    first gate into the cavity beginning at a first time;-   a second valve controlling delivery of the fluid material through    the second gate beginning at a second time subsequent to the first    time such that the fluid material has entered the cavity through the    first gate and approached the second gate prior to the second time;-   the second valve comprising an actuator interconnected to a valve    pin having a tip end, the actuator moving the valve pin continuously    upstream along a path of travel between a downstream gate closed    position and an intermediate upstream gate open position, the    downstream gate closed position being a position wherein the tip end    of the valve pin obstructs the second gate to prevent fluid material    from flowing into the mold cavity, the intermediate upstream gate    open position being a predetermined position between the downstream    gate closed position and a fully open, end of stroke position    upstream of the intermediate upstream gate open position;-   a controller interconnected to the actuator that controls movement    of the actuator at least in part according to instructions that    instruct the actuator to move the valve pin continuously upstream at    one or more selected velocities over the course of travel of the    valve pin from the downstream gate closed position to the    intermediate upstream gate open position.

In such an embodiment, the actuator can comprise an electrically drivenmotor interconnected to the valve pin that moves the valve pin at acontrollably variable rate according to an electrical or electronicsignal received from the controller that is controllably variable.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and further advantages of the invention may be betterunderstood by referring to the following description in conjunction withthe accompanying drawings in which:

FIG. 1 is a schematic cross-sectional side view of one embodiment of theinvention showing a mold having a valve with a gate injecting at acentral location in the cavity and a pair of lateral or distal valvesinjecting into the same cavity at lateral or distal locations, thecenter gate with center actuator 940 having been opened and shown closedsuch that a first shot of fluid material has entered the cavity andtraveled past the position of the lateral sequential gates, the lateralgates shown being open with their valve pin having traveled along anupstream restricted flow path RP allowing a second sequential shot offluid material to flow into and merge with the first shot of materialfrom the center gate within the cavity;

FIGS. 1A-1E are schematic cross-sectional close-up views of the centerand one of the lateral gates of the FIG. 1 apparatus showing variousstages of the progress of injection;

FIG. 2 is a schematic diagram of an embodiment of the invention showinggenerically a hydraulically actuated valve and its interconnection tothe hydraulic system and the control system for causing the valve pin towithdraw at the beginning of a cycle at predetermined reduced velocityfor a predetermined amount of time;

FIGS. 2A and 2B are schematic cross-sectional views of the hydraulicvalves and restrictors used in the system of FIG. 1 according to theinvention;

FIGS. 3A-3B show tapered end valve pin positions at various times andpositions between a starting closed position as in FIG. 3A and variousupstream opened positions, RP representing a selectable path length overwhich the velocity of withdrawal of the pin upstream from the gateclosed position to an open position is reduced (via a controllable flowrestrictor) relative to the velocity of upstream movement that the valvepin would normally have over the uncontrolled velocity path FOV when thehydraulic pressure is normally at full pressure and pin velocity is atits maximum;

FIGS. 4A-4B show a system having a valve pin that has a cylindricallyconfigured tip end, the tips ends of the pins being positioned atvarious times and positions between a starting closed position as inFIG. 4A and various upstream opened positions, RP wherein RP representsa path over which the velocity of withdrawal of the pin upstream fromthe gate closed position to an open position is reduced (via acontrollable flow restrictor or electric actuator) relative to thevelocity of upstream movement that the valve pin would normally haveover the uncontrolled velocity path FOV when the hydraulic pressure of ahydraulic actuator is normally at full pressure and pin velocity is atits maximum;

FIGS. 5A-5D are a series of plots of pin velocity versus time each plotrepresenting a different example of the opening of a gate lateral to acentral gate via continuous upstream withdrawal of a valve pin at onerate or set of rates over an initial flow path RP and at another higherrate or set of rates of upstream withdrawal of the valve pin beginningat a pin position of FOP and beyond when the fluid material flow istypically at a maximum unrestricted rate of flow through the open gatewithout any restriction or obstruction from the tip end of the pin.

DETAILED DESCRIPTION

FIG. 1 shows a system 10 with a central nozzle 22 feeding moltenmaterial from an injection molding machine through a main inlet 18 to adistribution channel 19 of a manifold 40. The distribution channel 19commonly feeds three separate nozzles 20, 22, 24 which all commonly feedinto a common cavity 30 of a mold 42. One of the nozzles 22 iscontrolled by actuator 940 and arranged so as to feed into cavity 30 atan entrance point or gate that is disposed at about the center 32 of thecavity. As shown, a pair of lateral nozzles 20, 24 feed into the cavity30 at gate locations that are distal 34, 36 to the center gate feedposition 32.

As shown in FIGS. 1, 1A the injection cycle is a cascade process whereinjection is effected in a sequence from the center nozzle 22 first andat a later predetermined time from the lateral nozzles 20, 24. As shownin FIG. 1A the injection cycle is started by first opening the pin 1040of the center nozzle 22 and allowing the fluid material 100 (typicallypolymer or plastic material) to flow up to a position 100 a in thecavity just before 100 b the distally disposed entrance into the cavity34, 36 of the gates of the lateral nozzles 24, 20 as shown in FIG. 1A.After an injection cycle is begun, the gate of the center injectionnozzle 22 and pin 1040 is typically left open only for so long as toallow the fluid material to travel to a position 100 p just past thepositions 34, 36. Once the fluid material has travelled just past 100 pof the lateral gate positions 34, 36, the center gate 32 of the centernozzle 22 is typically closed by pin 1040 as shown in FIGS. 1B, 1C, 1Dand 1E. The lateral gates 34, 36 are then opened by upstream withdrawalof lateral nozzle pins 1041, 1042 as shown in FIGS. 1B-1E. As describedbelow, the rate of upstream withdrawal or travel velocity of lateralpins 1041, 1042 is controlled as described below.

In alternative embodiments, the center gate 32 and associated actuator940 and valve pin 1040 can remain open at, during and subsequent to thetimes that the lateral gates 34, 36 are opened such that fluid materialflows into cavity 30 through both the center gate 32 and one or both ofthe lateral gates 34, 36 simultaneously.

When the lateral gates 34, 36 are opened and fluid material NM isallowed to first enter the mold cavity into the stream 102 p that hasbeen injected from center nozzle 22 past gates 34, 36, the two streamsNM and 102 p mix with each other. If the velocity of the fluid materialNM is too high, such as often occurs when the flow velocity of injectionfluid material through gates 34, 36 is at maximum, a visible line ordefect in the mixing of the two streams 102 p and NM will appear in thefinal cooled molded product at the areas where gates 34, 36 inject intothe mold cavity. By injecting NM at a reduced flow rate for a relativelyshort period of time at the beginning when the gate 34, 36 is firstopened and following the time when NM first enters the flow stream 102p, the appearance of a visible line or defect in the final moldedproduct can be reduced or eliminated.

The rate or velocity of upstream withdrawal of pins 1041, 1042 startingfrom the closed position is controlled via controller 16, FIGS. 1, 2which controls the rate and direction of flow of hydraulic fluid fromthe drive system 700 to the actuators 940, 941, 942. A “controller,” asused herein, refers to electrical and electronic control apparati thatcomprise a single box or multiple boxes (typically interconnected andcommunicating with each other) that contain(s) all of the separateelectronic processing, memory and electrical signal generatingcomponents that are necessary or desirable for carrying out andconstructing the methods, functions and apparatuses described herein.Such electronic and electrical components include programs,microprocessors, computers, PID controllers, voltage regulators, currentregulators, circuit boards, motors, batteries and instructions forcontrolling any variable element discussed herein such as length oftime, degree of electrical signal output and the like. For example acomponent of a controller, as that term is used herein, includesprograms, controllers and the like that perform functions such asmonitoring, alerting and initiating an injection molding cycle includinga control device that is used as a standalone device for performingconventional functions such as signaling and instructing an individualinjection valve or a series of interdependent valves to start aninjection, namely move an actuator and associated valve pin from a gateclosed to a gate open position. In addition, although fluid drivenactuators are employed in typical or preferred embodiments of theinvention, actuators powered by an electric or electronic motor or drivesource can alternatively be used as the actuator component.

As shown in FIGS. 2A, 2B, a supply of hydraulic fluid 14 is fed firstthrough a directional control valve 750 mechanism that switches thehydraulic fluid flow to the actuator cylinders in either of twodirections: fluid out to withdraw the pin upstream, FIG. 2A, and fluidin to drive the pin downstream, FIG. 2B. At the beginning of aninjection cycle the gate of a lateral valve 34, 36 is closed and thehydraulic system is in the directional configuration of FIG. 2B. When acycle is started, the directional configuration of the directional valve750 of the hydraulic system 700 is switched by controller 16 to theconfiguration of FIG. 2A. The hydraulic system includes a flowrestriction valve 600 that can vary the rate of flow of hydraulic fluidto the actuator 941 under the control of the controller 16 to vary therate of travel, upstream or downstream of the piston of the actuator 941which in turn controls the direction and rate of travel of pin 1041.Although not shown in FIGS. 2A, 2B, the hydraulic system 700 controlsthe direction and rate of travel of the pistons of actuators 940 and 942in a manner similar to the manner of control of actuator 941 via theconnections shown in FIG. 1.

The user programs controller 16 via data inputs on a user interface toinstruct the hydraulic system 700 to drive pins 1041, 1042 at anupstream velocity of travel for a predetermined amount of time that isreduced relative to a maximum velocity that the hydraulic system candrive the pins 1041, 1042 to travel. As described below, such reducedpin withdrawal rate or velocity is executed for a preselected amount oftime that is less than the time of the entire injection cycle, thelatter part of the injection cycle being executed with the pins 1041,1042 being withdrawn at higher velocities. A typical amount of time overwhich the pins are instructed to withdraw at a reduced velocity isbetween about 0.25 and about 10 seconds, more typically between about0.5 and about 5 seconds, the entire injection cycle time typically beingbetween about 4 seconds and about 30 seconds, more typically betweenabout 6 seconds and about 12 seconds.

FIG. 1 shows position sensors 950, 951, 952 which sense the position ofthe actuator cylinders 940, 941, 942 and their associated valve pins(such as 1040, 1041, 1042) and feeds such position information tocontroller 16 for monitoring purposes. Such information may or may notbe used or included in conjunction with the apparatus and method of thepresent invention and is not a necessary component thereof given thatthe user selects and inputs time, and not position, to the controller 16as the essential variable for controlling drive of the valve pin 1040,1041, 1042 and actuator(s) 940-942 upstream at a selected less thanmaximum velocity.

As shown, fluid material 18 is injected from an injection machine into amanifold runner 19 and further downstream into the bores 44, 46 of thelateral nozzles 24, 22 and ultimately downstream through the gates 32,34, 36. When the pins 1041, 1042 are withdrawn upstream to a positionwhere the tip end of the pins 1041 are in a fully upstream open positionsuch as shown in FIG. 1D, the rate of flow of fluid material through thegates 34, 36 is at a maximum. However when the pins 1041, 1042 areinitially withdrawn beginning from the closed gate position, FIG. 1A, tointermediate upstream positions, FIGS. 1B, 1C, a gap 1154, 1156 thatrestricts the velocity of fluid material flow is formed between theouter surfaces 1155 of the tip end of the pins 44, 46 and the innersurfaces 1254, 1256 of the gate areas of the nozzles 24, 20. Therestricted flow gap 1154, 1156 remains small enough to restrict andreduce the rate of flow of fluid material 1153 through gates 34, 36 to arate that is less than maximum flow velocity over a travel distance RPof the tip end of the pins 1041, 1042 going from closed to upstream asshown in FIGS. 1, 1B, 1C, 1E and 3B, 4B.

The pins 1041 can be controllably withdrawn at one or more reducedvelocities (less than maximum) for one or more periods of time over theentirety of the length of the path RP over which flow of mold material1153 is restricted. Preferably the pins are withdrawn at a reducedvelocity over more than about 50% of RP and most preferably over morethan about 75% of the length RP. As described below with reference toFIGS. 3B, 4B, the pins 1041 can be withdrawn at a higher or maximumvelocity at the end COP2 of a less than complete restricted moldmaterial flow path RP2.

The trace or visible lines that appear in the body of a part that isultimately formed within the cavity of the mold on cooling above can bereduced or eliminated by reducing or controlling the velocity of the pin1041, 1042 opening or upstream withdrawal from the gate closed positionto a selected intermediate upstream gate open position that ispreferably 75% or more of the length of RP.

The periods of time over which the pins 1041, 1042 are withdrawn atreduced velocities are typically determined empirically by trial anderror runs. One or more, typically multiple, trial injection cycle runsare carried out to make specimen parts from the mold. Each trialinjection cycle run is carried out using a different period or periodsof time at which the pins 1041, 1042 are withdrawn at one or morereduced velocities over the trial period(s) of time, and the quality ofthe parts produced from all such trial runs are compared to determinethe optimum quality producing time(s) of reduced velocity pinwithdrawals. When the optimum time(s) have been determined, thecontroller is programmed to carry out an injection cycle where the pinwithdrawal velocities of pins 1041, 1042 are reduced for thepredetermined amounts of time at the predetermined reduced withdrawalrates.

RP can be about 1-8 mm in length and more typically about 2-6 mm andeven more typically 2-4 mm in length. As shown in FIG. 2 in such anembodiment, a control system or controller 16 is preprogrammed tocontrol the sequence and the rates of valve pin 1040, 1041, 1042 openingand closing. The controller 16 controls the rate of travel, namelyvelocity of upstream travel, of a valve pin 1041, 1042 from its gateclosed position for at least the predetermined amount of time that isselected to withdraw the pin at the selected reduced velocity rate.

The velocity of withdrawal of the valve pins 1041, 1042 is determined byregulation of the flow of hydraulic drive fluid that is pumped from asupply 14 to the actuators 941, 942 through a flow restrictor valve 600,FIGS. 1, 2, 2A, 2B. When the flow restrictor valve 600 is completelyopen, namely 100% open, allowing maximum flow of the pressurizedhydraulic fluid to the actuator cylinders, the valve pins 1041, 1042 aredriven at a maximum upstream travel velocity. According to theinvention, the degree of openness of the flow restrictor valve isadjusted for a select period of time beginning from the gate closedposition of the pin to less than 100% open. Adjustment of the flowrestrictor valve 600 to less than 100% open thus reduces the rate andvolume flow of pressurized hydraulic fluid to the actuator cylindersthus in turn reducing the velocity of upstream travel of the pins 1041,1042 for the selected period of time. At the end of the select period oftime of reduced openness of the valve 600, the valve 600 is opened toits 100% open position to allow the actuator pistons and the valve pins1041, 1042 to be driven at maximum upstream velocity in order to reducethe cycle time of the injection cycle.

The valve 600 typically comprises a restrictor valve that iscontrollably positionable anywhere between completely closed (0% open)and completely open (100% open). Adjustment of the position of therestrictor valve 600 is typically accomplished via a source ofelectrical power that controllably drives an electromechanical mechanism602 that causes the valve to rotate such as a rotating spool that reactsto a magnetic or electromagnetic field created by the electrical signaloutput of the controller 16, namely an output of electrical energy,electrical power, voltage, current or amperage the degree or amount ofwhich can be readily and controllably varied by conventional electricaloutput devices. The electro-mechanism 602 is controllably drivable tocause the valve 600 to open or close to a degree of openness that isproportional to the amount or degree of electrical energy that is inputto drive the electro-mechanism 602. The velocity of upstream withdrawaltravel of the pins 1041, 1042 are in turn proportional to the degree ofopenness of the valve 600. Thus the rate of upstream travel of the pins1041, 1042 is proportional to the amount or degree of electrical energythat is input to the electromechanism 602 that drives valves 600. Theelectromechanism 602 that is selected for driving the valve 600establishes in the first instance the maximum amount of electricalenergy or power (such as voltage or current) that is required to openthe valve to its 100% open position. A control for setting the amount ordegree of electrical energy or power input to the motor is containedwithin the controller 16. Controller 16 includes an interface thatenables the user to input any selected fraction or percentage of themaximum electrical energy or power needed to adjust the valve 600 toless than 100% open for any preselected amount of time beginning fromthe gate closed position of the valve pins 1041, 1042 and theirassociated actuators 941, 942. Thus the user selects a reduced upstreamvelocity of the pins 1041, 1042 by inputting to the controller 16 apercentage of the maximum amount of electrical energy or power input(voltage or current) needed to open the valve 600 to 100% open. The userinputs such selections into the controller 16. The user also selects theperiod of time over which the valve 600 is partially opened and inputssuch a selection into the controller 16. The controller 16 includesconventional programming or circuitry that receives and executes theuser inputs. The controller may include programming or circuitry thatenables the user to input as a variable a selected pin velocity ratherthan a percentage of electrical energy, the programming of thecontroller automatically converting the inputs by the user toappropriate instructions for reduced electrical input to theelectro-mechanism that that drives the valve 600.

Typically the user selects one or more reduced velocities that are lessthan about 90% of the maximum velocity (namely velocity when the valve600 is fully open), more typically less than about 75% of the maximumvelocity and even more typically less than about 50% of the maximumvelocity at which the pins 1041, 1042 are drivable by the hydraulicsystem. The actual maximum velocity at which the actuators 941, 942 andtheir associated pins 1041, 1042 are driven is predetermined byselection of the size and configuration of the actuators 941, 942, thesize and configuration of the restriction valve 600 and the degree ofpressurization and type of hydraulic drive fluid selected for use by theuser. The maximum drive rate of the hydraulic system is predetermined bythe manufacturer and the user of the system and is typically selectedaccording to the application, size and nature of the mold and theinjection molded part to be fabricated.

As shown by the series of examples of programs illustrated in FIGS.5A-5D one or more reduced pin velocities can be selected and the pindriven by restricted hydraulic fluid flow (or by reduced velocity driveby an electric actuator) for any one or more selected periods of timebetween the gate closed (X and Y axis zero position) and the finalintermediate upstream open gate position (4 mm for example in the FIG.5A example, 5 mm in the FIG. 5B example) at which point the pin 1041,1042 is driven to travel upstream at maximum upstream travel velocity(as shown, 100 mm/sec in the FIGS. 5A-5D examples). In the FIG. 5Aexample, the reduced pin velocity is selected as 50 mm/sec. In practicethe actual velocity of the pin may or may not be precisely known, the Yvelocity axis corresponding (and generally being proportional) to thedegree of electrical energy input to the motor that controls the openingof the flow restriction valve, 100 mm/sec corresponding to the valve 600being completely 100% open (and pin being driven at maximum velocity);and 50 mm/sec corresponding to 50% electrical energy input to theelectromechanism that drives the restriction valve 600 to one-half ofits maximum 100% degree of openness. In the FIG. 5A example, the timeover which the valve pin 1041, 1042 is programmed to travel at thereduced 50 mm/sec velocity is 0.08 seconds. Also in this example, thevalve pin 1041 travels to intermediate upstream gate open positionsbetween 0 mm (gate closed) and about 4 mm upstream at the reduced 50mm/sec velocity. After the pin 1041, 1042 has been driven for thepreselected 0.08 seconds (reaching an upstream position of about 4 mmfrom the gate closed position), the controller 16 instructs theelectro-mechanism that drives the valve 600 (typically a magnetic orelectromagnetic field driven device such as a spool) to open therestrictor valve 600 to full 100% open at which time the pin (and itsassociated actuator piston) are driven by the hydraulic system at themaximum travel rate 100 mm/sec for the predetermined, given pressurizedhydraulic system.

FIGS. 5B-5D illustrate a variety of alternative examples for driving thepin 1041, 1042 at reduced velocities for various durations of time. Forexample as shown in FIG. 5B, the pin is driven for 0.02 seconds at 25mm/sec, then for 0.06 seconds at 75 mm/sec and then allowed to go tofull valve open velocity shown as 100 mm/sec. Full valve open or maximumvelocity is typically determined by the nature of hydraulic (orpneumatic) valve or motor drive system that drives the valve pin. In thecase of a hydraulic (or pneumatic) system the maximum velocity that thesystem is capable of implementing is determined by the nature, designand size of the pumps, the fluid delivery channels, the actuator, thedrive fluid (liquid or gas), the restrictor valves and the like.

As shown in FIGS. 5A-5D, when the pin reaches the end of the reducedvelocity period, the valve 600 can be instructed to assume the full openposition essentially instantaneously or alternatively can be instructedto take a more gradual approach up, between 0.08 and 0.12 seconds, tothe maximum valve openness as shown in FIG. 5D. In all cases thecontroller 16 instructs the valve pin 1041, 1042 to travel continuouslyupstream rather than follow a profile where the pin might travel in adownstream direction during the course of the injection cycle. Mostpreferably, the actuator, valve pin, valves and fluid drive system areadapted to move the valve pin between a gate closed position and amaximum upstream travel position that defines an end of stroke positionfor the actuator and the valve pin. Most preferably the valve pin ismoved at the maximum velocity at one or more times or positions over thecourse of upstream travel of the valve pin past the upstream gate openposition. Alternatively to the hydraulic system depicted and described,a pneumatic or gas driven system can be used and implemented in the samemanner as described above for a hydraulic system.

Preferably, the valve pin and the gate are configured or adapted tocooperate with each other to restrict and vary the rate of flow of fluidmaterial 1153, FIGS. 3A-3B, 4A-4B over the course of travel of the tipend of the valve pin through the restricted velocity path RP. Mosttypically as shown in FIGS. 3A, 3B the radial tip end surface 1155 ofthe end 1142 of pin 1041, 1042 is conical or tapered and the surface ofthe gate 1254 with which pin surface 1155 is intended to mate to closethe gate 34 is complementary in conical or taper configuration.Alternatively as shown in FIGS. 4A, 4B, the radial surface 1155 of thetip end 1142 of the pin 1041, 1042 can be cylindrical in configurationand the gate can have a complementary cylindrical surface 1254 withwhich the tip end surface 1155 mates to close the gate 34 when the pin1041 is in the downstream gate closed position. In any embodiment, theoutside radial surface 1155 of the tip end 1142 of the pin 1041 createsrestricted a restricted flow channel 1154 over the length of travel ofthe tip end 1142 through and along restricted flow path RP thatrestricts or reduces the volume or rate of flow of fluid material 1153relative to the rate of flow when the pin 1041, 1042 is at a full gateopen position, namely when the tip end 1142 of the pin 1041 hastravelled to or beyond the length of the restricted flow path RP (whichis, for example the 4 mm upstream travel position of FIGS. 5A-5C).

In one embodiment, as the tip end 1142 of the pin 1041 continues totravel upstream from the gate closed GC position (as shown for examplein FIGS. 3A, 4A) through the length of the RP path (namely the pathtravelled for the predetermined amount of time), the rate of materialfluid flow 1153 through restriction gap 1154 through the gate 34 intothe cavity 30 continues to increase from 0 at gate closed GC position toa maximum flow rate when the tip end 1142 of the pin reaches a positionFOP (full open position), FIGS. 5A-5D, where the pin is no longerrestricting flow of injection mold material through the gate. In such anembodiment, at the expiration of the predetermined amount of time whenthe pin tip 1142 reaches the FOP (full open) position FIGS. 5A, 5B, thepin 1041 is immediately driven by the hydraulic system at maximumvelocity FOV (full open velocity) typically such that the restrictionvalve 600 is opened to full 100% open.

In alternative embodiments, when the predetermined time for driving thepin at reduced velocity has expired and the tip 1142 has reached the endof restricted flow path RP2, the tip 1142 may not necessarily be in aposition where the fluid flow 1153 is not still being restricted. Insuch alternative embodiments, the fluid flow 1153 can still berestricted to less than maximum flow when the pin has reached thechangeover position COP2 where the pin 1041 is driven at a higher,typically maximum, upstream velocity FOV. In the alternative examplesshown in the FIG. 3B example when the predetermined time has expired fordriving the pin at reduced velocity and the tip end 1142 has reachedchangeover point COP, the tip end 1142 of the pin 1041 (and its radialsurface 1155) no longer restricts the rate of flow of fluid material1153 through the gap 1154 because the gap 1154 has increased to a sizethat no longer restricts fluid flow 1153 below the maximum flow rate ofmaterial 1153. Thus in one of the examples shown in FIG. 3B the maximumfluid flow rate for injection material 1153 is reached at the upstreamposition COP of the tip end 1142. In another example shown in FIG. 3B4B, the pin 1041 can be driven at a reduced velocity over a shorter pathRP2 that is less than the entire length of the restricted mold materialflow path RP and switched over at the end COP2 of the shorter restrictedpath RP2 to a higher or maximum velocity FOV. In the FIGS. 5A, 5Bexamples, the upstream FOP position is about 4 mm and 5 mm respectivelyupstream from the gate closed position. Other alternative upstream FOPpositions are shown in FIGS. 5C, 5D.

In another alternative embodiment, shown in FIG. 4B, the pin 1041 can bedriven and instructed to be driven at reduced or less than maximumvelocity over a longer path length RP3 having an upstream portion URwhere the flow of injection fluid mold material is not restricted butflows at a maximum rate through the gate 34 for the given injection moldsystem. In this FIG. 4B example the velocity or drive rate of the pin1041 is not changed over until the tip end of the pin 1041 or actuator941 has reached the changeover position COP3. As in other embodiments, aposition sensor senses either that the valve pin 1041 or an associatedcomponent has travelled the path length RP3 or reached the end COP3 ofthe selected path length and the controller receives and processes suchinformation and instructs the drive system to drive the pin 1041 at ahigher, typically maximum velocity upstream. In another alternativeembodiment, the pin 1041 can be driven at reduced or less than maximumvelocity throughout the entirety of the travel path of the pin during aninjection cycle from the gate closed position GC up to the end-of-strokeEOS position, the controller 16 being programmed to instruct the drivesystem for the actuator to be driven at one or more reduced velocitiesfor the time or path length of an entire closed GC to fully open EOScycle.

In the FIGS. 5A-5D examples, FOV is 100 mm/sec. Typically, when the timeperiod for driving the pin 1041 at reduced velocity has expired and thepin tip 1142 has reached the position COP, COP2, the restriction valve600 is opened to full 100% open velocity FOV position such that the pins1041, 1042 are driven at the maximum velocity or rate of travel that thehydraulic system is capable of driving the actuators 941, 942.Alternatively, the pins 1041, 1042 can be driven at a preselected FOVvelocity that is less than the maximum velocity at which the pin iscapable of being driven when the restriction valve 600 is fully open butis still greater than the selected reduced velocities that the pin isdriven over the course of the RP, RP2 path to the COP, COP2 position.

At the expiration of the predetermined reduced velocity drive time, thepins 1041, 1042 are typically driven further upstream past the COP, COP2position to a maximum end-of-stroke EOS position. The upstream COP, COP2position is downstream of the maximum upstream end-of-stroke EOS openposition of the tip end 1142 of the pin. The length of the path RP orRP2 is typically between about 2 and about 8 mm, more typically betweenabout 2 and about 6 mm and most typically between about 2 and about 4mm. In practice the maximum upstream (end of stroke) open position EOSof the pin 1041, 1042 ranges from about 8 mm to about 18 inches upstreamfrom the closed gate position GC.

The controller 16 includes a processor, memory, user interface andcircuitry and/or instructions that receive and execute the user inputsof percentage of maximum valve open or percentage of maximum voltage orcurrent input to the motor drive for opening and closing the restrictionvalve, time duration for driving the valve pin at the selected valveopenings and reduced velocities.

In alternative embodiments the controller can include a processor andinstructions that receive pin position information and signals from aposition sensor and calculate the real time velocity of the pin from thepin position data at one or more times or positions over the course ofthe pin travel through the RP, RP2, RP3 path length and/or beyond. Suchcalculations of velocity can be intermittent or continuous throughoutthe cycle. In such an embodiment, the calculated pin velocity isconstantly compared in real time to a predetermined target profile ofpin velocities over the predetermined time period for reduced velocityand the velocity of the pin is adjusted in real time by the controller16 to conform to the reduced velocity profile for the predeterminedamount of time. In this embodiment as in all previously describedembodiments, the pin is moved continuously upstream at all times betweenthe gate closed position and all positions upstream of the gate closedposition. Such control systems are described in greater detail in forexample U.S. Patent Publication no. 20090061034 the disclosure of whichis incorporated herein by reference.

As discussed above, control over the velocity of pin movement in anembodiment where the pin is driven by a hydraulic or pneumatic actuatoris typically accomplished by controlling the degree of openness of thefluid restriction valve 600, control over velocity and drive rate orposition of valve 600 being the same functions in terms of theinstructions, microprocessor design or computer software that carriesout instructing and implementing the velocity or drive rate adjustmentto the valve pin or actuator. Where the position sensing system sensesthe position of the pin or other component multiple times throughout thecourse of the pin or other component movement, and real time velocitycan be calculated by the controller 16, a program or instructions can bealternatively used to receive a velocity data input by the user to thecontroller 16 as the variable to be stored and processed instead of apredetermined voltage or current input Where an actuator that comprisesan electric motor is used as the drive mechanism for moving the valvepin 1041, 1042 instead of a fluid driven actuator, the controller 16 cansimilarly be programmed to receive and process velocity data input as avariable for controlling the velocity or rate of drive of the electricactuator.

What is claimed is:
 1. An apparatus for controlling the rate of flow ofa fluid material during a sequentially gated molding process wherein afluid mold material is delivered through first and second gates into acommon mold cavity, the apparatus comprising: a first valve controllingdelivery of the fluid material through the first gate into the cavitybeginning at a first time; a second valve controlling delivery of thefluid material through the second gate beginning at a second timesubsequent to the first time such that the fluid material has enteredthe cavity through the first gate and approached the second gate priorto the second time; the second valve comprising an actuatorinterconnected to a valve pin having a tip end, the actuator moving thevalve pin upstream along a path of travel between a downstream gateclosed position and one or more intermediate upstream gate openpositions, the downstream gate closed position being a position whereinthe tip end of the valve pin obstructs the second gate to prevent fluidmaterial from flowing into the mold cavity, the one or more intermediateupstream gate open positions being predetermined positions between thedownstream gate closed position and an end of stroke position upstreamof the one or more intermediate upstream gate open positions, whereinthe second gate is partially open when the valve pin is in the one ormore intermediate upstream gate open positions and the second gate ismore fully open when the valve pin is in the end of stroke position; acontroller interconnected to the actuator that controls movement of theactuator at least in part according to instructions that instruct theactuator to move the valve pin: upstream at one or more selectedintermediate velocities for one or more selected lengths of time overthe course of travel of the valve pin from the downstream gate closedposition to the one or more intermediate upstream gate open positions;upstream at a higher upstream velocity than the one or more selectedintermediate velocities upon expiration of the one or more selectedlengths of time.
 2. The apparatus of claim 1 wherein the tip end of thevalve pin and the second gate are adapted to cooperate with each otherto restrict rate of flow of the fluid material through the gate over thecourse of the path of travel of the valve pin from the downstream gateclosed position to the one or more intermediate upstream gate openpositions.
 3. The apparatus of claim 1 wherein the tip end surface ofthe valve pin comprises a cylindrical or tapered configuration and thesecond gate has a complementary cylindrical surface that mates with thecylindrical or tapered configuration of the tip end surface to close thesecond gate.
 4. The apparatus of claim 1 wherein the one or moreselected intermediate velocities are less than about 75% of the highervelocity.
 5. The apparatus of claim 1 wherein the controller includesinstructions that instruct the actuator to drive the valve pincontinuously upstream from the gate closed position to the end of strokeposition.
 6. The apparatus of claim 1 wherein the length of travelbetween the downstream gate closed position and the furthest upstream ofthe one or more intermediate upstream gate open positions is betweenabout 1 mm and about 5 mm.
 7. The apparatus of claim 1 wherein in theone of more intermediate upstream positions the tip end of the valve pinrestricts the flow of the fluid material to less than a maximum rate offlow into the second gate.
 8. The apparatus of claim 7 wherein betweenthe one or more intermediate open positions and the end of strokeposition, the tip end of the valve pin allows the maximum rate of flowinto the second gate.
 9. The apparatus of claim 1 wherein the actuatorcomprises an electrically driven motor interconnected to the valve pinand adapted to move the valve pin at a controllably variable rate.
 10. Amethod for controlling the rate of flow of a fluid material during asequentially gated molding process wherein a fluid mold material isdelivered through first and second gates into a common mold cavity, themethod comprising: controlling delivery of the fluid material throughthe first gate into the cavity beginning at a first time; controllingdelivery of the fluid material through the second gate beginning at asecond time subsequent to the first time such that the fluid materialhas entered the cavity through the first gate and approached the secondgate prior to the second time; wherein the step of controlling deliverythrough the second gate comprises an actuator interconnected to a valvepin having a tip end, the actuator moving the valve pin upstream along apath of travel between a downstream gate closed position and one or moreintermediate upstream gate open positions, the downstream gate closedposition being a position wherein the tip end of the valve pin obstructsthe second gate to prevent fluid material from flowing into the moldcavity, the one or more intermediate upstream gate open positions beingpredetermined positions between the downstream gate closed position andan end of stroke position upstream of the one or more intermediateupstream gate open positions, wherein the second gate is partially openwhen the valve pin is in the one or more intermediate upstream gate openpositions and the second gate is more fully open when the valve pin isin the end of stroke position; controlling, via an controllerinterconnected to the actuator, movement of the actuator at least inpart according to instructions that instruct the actuator to move thevalve pin: upstream at one or more selected intermediate velocities forone or more selected lengths of time over the course of travel of thevalve pin from the downstream gate closed position to the one or moreintermediate upstream gate open positions; upstream at a higher upstreamvelocity than the one or more selected intermediate velocities uponexpiration of the one or more selected lengths of time.
 11. The methodof claim 10 wherein the tip end of the valve pin and the second gate areadapted to cooperate with each other to provide a restricted flowchannel that increases the rate of flow of the fluid material throughthe second gate over the course of at least a portion of the upstreamtravel of the valve pin from the downstream gate closed position to theone or more intermediate upstream gate open positions.
 12. The method ofclaim 10 wherein the tip end surface of the valve pin comprises acylindrical or tapered configuration and the second gate has acomplementary cylindrical or tapered surface that mates with thecylindrical or tapered configuration of the tip end surface to close thesecond gate.
 13. The method of claim 10 wherein the one or more selectedintermediate velocities are less than about 75% of the higher velocity.14. The method of claim 10 wherein the controller includes instructionsthat instruct the actuator to drive the valve pin continuously upstreamfrom the date closed position to the end of stroke position.
 15. Themethod of claim 10 wherein the length of travel between the downstreamgate closed position and the furthest upstream of the one or moreintermediate upstream gate open positions is between about 1 mm andabout 5 mm.
 16. The method of claim 10 wherein in the one of moreintermediate upstream positions the tip end of the valve pin restrictsthe flow of the fluid material to less than a maximum rate of flow intothe second gate.
 17. The method of claim 16 wherein between the one ormore intermediate open positions and the end of stroke position, the tipend of the valve pin allows the maximum rate of flow into the secondgate.
 18. The method of claim 10 wherein the actuator comprises anelectrically driven motor interconnected to the valve pin and adapted tomove the valve pin at a controllably variable rate.
 19. A method ofperforming an injection molding cycle comprising operating the apparatusof claim 1 to inject the fluid material into the cavity of the moldduring the course of an injection molding cycle.
 20. The apparatus ofclaim 1 wherein the controller includes instructions that instruct theactuator to drive the valve pin continuously upstream from the gateclosed position to the end of stroke position.
 21. Method of claim 10wherein the controller includes instructions that instruct the actuatorto drive the valve pin continuously upstream from the gate closedposition to the end of stroke position.
 22. Method of claim 19 whereinthe controller includes instructions that instruct the actuator to drivethe valve pin continuously upstream from the gate closed position to theend of stroke position.
 23. An apparatus for controlling the rate offlow of a fluid material during a sequentially gated molding processwherein a fluid mold material is delivered through first and secondgates into a common mold cavity, the apparatus comprising: a first valvecontrolling delivery of the fluid material through the first gate intothe cavity beginning at a first time; a second valve controllingdelivery of the fluid material through the second gate beginning at asecond time subsequent to the first time such that the fluid materialhas entered the cavity through the first gate and approached the secondgate prior to the second time; the second valve comprising an actuatorinterconnected to a valve pin having a tip end, the actuator moving thevalve pin upstream along a path of travel between a downstream gateclosed position and one or more intermediate upstream gate openpositions, the downstream gate closed position being a position whereinthe tip end of the valve pin obstructs the second gate to prevent fluidmaterial from flowing into the mold cavity, the one or more intermediateupstream gate open positions being predetermined positions between thedownstream gate closed position and an end of stroke position upstreamof the one or more intermediate upstream gate open positions, whereinthe second gate is partially open when the valve pin is in the one ormore intermediate upstream gate open positions and the second gate ismore fully open when the valve pin is in the end of stroke position; acontroller interconnected to the actuator that controls movement of theactuator at least in part according to instructions that instruct theactuator to move the valve pin: upstream at one or more selectedintermediate velocities for one or more selected lengths of time overthe course of travel of the valve pin from the downstream gate closedposition to the one or more intermediate upstream gate open positions;upstream at a higher upstream velocity than the one or more selectedintermediate velocities upon expiration of the one or more selectedlengths of time, wherein the tip end of the valve pin and the gate areadapted to cooperate with each other to restrict rate of flow of thefluid material through the gate over the course of the path of travel ofthe valve pin from the downstream gate closed position to the one ormore intermediate upstream gate open positions, and wherein the valvepin is withdrawn at a reduced velocity over more than about 50% of thepath of travel of the valve pin from the downstream gate closed positionto the one or more intermediate upstream gate open positions.
 24. Theapparatus of claim 23 wherein the path of travel of the valve pin fromthe downstream gate closed position to the one or more intermediateupstream gate open positions is between about 1 and about 8 mm.
 25. Theapparatus of claim 24 wherein the path of travel of the valve pin fromthe downstream gate closed position to the one or more intermediateupstream gate open positions is between about 1 and about 5 mm.
 26. Theapparatus of claim 23 wherein the one or more selected intermediatevelocities are less than about 75% of the higher velocity.
 27. Theapparatus of claim 23 wherein the controller includes instructions thatinstruct the actuator to drive the valve pin continuously upstream fromthe gate closed position to the end of stroke position.
 28. Theapparatus of claim 20 wherein the tip end surface of the valve pincomprises a cylindrical or tapered configuration and the second gate hasa complementary cylindrical or tapered surface that mates with thecylindrical or tapered configuration of the tip end surface of the valvepin to close the second gate.
 29. Method of performing an injectionmolding cycle comprising operating an apparatus according to claim 23.30. The method of claim 29 wherein the controller includes instructionsthat instruct the actuator to drive the valve pin continuously upstreamfrom the gate closed position to the end of stroke position.
 31. Anapparatus for controlling the rate of flow of a fluid material during asequentially gated molding process wherein a fluid mold material isdelivered through first and second gates into a common mold cavity, theapparatus comprising: a first valve controlling delivery of the fluidmaterial through the first gate into the cavity beginning at a firsttime; a second valve controlling delivery of the fluid material throughthe second gate beginning at a second time subsequent to the first timesuch that the fluid material has entered the cavity through the firstgate and approached the second gate prior to the second time; the secondvalve comprising an actuator interconnected to a valve pin having a tipend, the actuator moving the valve pin upstream along a path of travelbetween a downstream gate closed position and one or more intermediateupstream gate open positions, the downstream gate closed position beinga position wherein the tip end of the valve pin obstructs the secondgate to prevent fluid material from flowing into the mold cavity, theone or more intermediate upstream gate open positions beingpredetermined positions between the downstream gate closed position andan end of stroke position upstream of the one or more intermediateupstream gate open positions, wherein the second gate is partially openwhen the valve pin is in the one or more intermediate upstream gate openpositions and the second gate is more fully open when the valve pin isin the end of stroke position; a controller interconnected to theactuator that controls movement of the actuator at least in partaccording to instructions that instruct the actuator to move the valvepin: upstream at one or more selected intermediate velocities for one ormore selected lengths of time over the course of travel of the valve pinfrom the downstream gate closed position to the one or more intermediateupstream gate open positions; upstream at a higher upstream velocitythan the one or more selected intermediate velocities upon expiration ofthe one or more selected lengths of time, wherein the path of travel ofthe valve pin from the downstream gate closed position to the one ormore intermediate upstream gate open positions is between about 1 andabout 8 mm.
 32. Apparatus according to claim 31 wherein the tip end ofthe valve pin and the gate are adapted to cooperate with each other torestrict rate of flow of the fluid material through the gate over thecourse of the path of travel of the valve pin from the downstream gateclosed position to the one or more intermediate upstream gate openpositions, and wherein the valve pin is withdrawn at a reduced velocityover more than about 50% of the path of travel of the valve pin from thedownstream gate closed position to the one or more intermediate upstreamgate open positions.
 33. The apparatus of claim 31 wherein the tip endsurface of the valve pin comprises a cylindrical or taperedconfiguration and the second gate has a complementary cylindrical ortapered surface that mates with the cylindrical or tapered configurationof the tip end surface to close the second gate.
 34. Apparatus of claim31 wherein the one or more selected intermediate velocities are lessthan about 75% of the higher velocity.
 35. Method of performing aninjection molding cycle comprising operating an apparatus according toclaim
 31. 36. Apparatus of claim 31 wherein the controller includesinstructions that instruct the actuator to drive the valve pincontinuously upstream from the gate closed position to the end of strokeposition.
 37. Method of claim 35 wherein the controller includesinstructions that instruct the actuator to drive the valve pincontinuously upstream from the gate closed position to the end of strokeposition.
 38. An apparatus for controlling the rate of flow of a fluidmaterial during a sequentially gated molding process wherein a fluidmold material is delivered through first and second gates into a commonmold cavity, the apparatus comprising: a first valve controllingdelivery of the fluid material through the first gate into the cavitybeginning at a first time; a second valve controlling delivery of thefluid material through the second gate beginning at a second timesubsequent to the first time such that the fluid material has enteredthe cavity through the first gate and approached the second gate priorto the second time; the second valve comprising an actuatorinterconnected to a valve pin having a tip end, the actuator moving thevalve pin upstream along a path of travel through a nozzle between adownstream gate closed position and one or more intermediate upstreamgate open positions, the downstream gate closed position being aposition wherein the tip end of the valve pin has a cylindrical ortapered configuration and the gate has a complementary cylindrical ortapered surface that mates with the cylindrical or tapered configurationof the tip end surface to close the second gate into a gate closedposition, the one or more intermediate upstream gate open positionsbeing predetermined positions between the downstream gate closedposition and an end of stroke position upstream of the one or moreintermediate upstream gate open positions, wherein a flow restrictiongap is formed between outer surfaces of the valve pin of the second gateand inner surfaces of the nozzle such that flow of fluid materialthrough the second gate is restricted when the valve pin is in the oneor more intermediate upstream gate open positions; the second gate beingmore fully open when the valve pin is in the end of stroke position; acontroller interconnected to the actuator that controls movement of theactuator at least in part according to instructions that instruct theactuator to move the valve pin: upstream at one or more selectedintermediate velocities for one or more selected lengths of time overthe course of travel of the valve pin from the downstream gate closedposition to the one or more intermediate upstream gate open positions;upstream at a higher upstream velocity than the one or more selectedintermediate velocities upon expiration of the one or more selectedlengths of time. positions.
 39. Apparatus of claim 38, wherein flow offluid material is at a maximum rate when the valve pin is in the end ofstroke position.
 40. Apparatus of claim 38 wherein the one or moreselected intermediate velocities are less than about 75% of the highervelocity.
 41. Apparatus of claim 38 wherein the controller includesinstructions that instruct the actuator to drive the valve pincontinuously upstream from the gate closed position to the end of strokeposition.
 42. Apparatus of claim 38 wherein the length of travel betweenthe downstream gate closed position and the furthest upstream of the oneor more intermediate upstream gate open positions is between about 1 mmand about 8 mm.
 43. Apparatus of claim 38 wherein between the one ormore intermediate open positions and the end of stroke position, the tipend of the valve pin allows a maximum rate of flow into the gate. 44.Apparatus of claim 38 wherein the actuator comprises an electricallydriven motor interconnected to the valve pin and adapted to move thevalve pin at a controllably variable rate.
 45. Apparatus of claim 38wherein the instructions instruct the actuator to drive the valve pinupstream beginning from the downstream gate closed position at highervelocity than the one or more selected intermediate velocities.
 46. Amethod for controlling the rate of flow of a fluid material from aninjection molding machine to a gate of a mold cavity, the methodcomprising performing an injection cycle by operating an apparatusaccording to claim
 38. 47. Method of claim 46 wherein the controllerincludes instructions that instruct the actuator to drive the valve pincontinuously upstream from the gate closed position to the end of strokeposition.
 48. Apparatus of claim 38 wherein the tip end surface of thevalve pin comprises a cylindrical or tapered configuration and thesecond gate has a complementary cylindrical or tapered surface thatmates with the cylindrical or tapered configuration of the tip endsurface to close the second gate.